This paper provides some critical review of the history and state of two elastic fracture mechanics (K and T) and relationship to crack paths. A particular attention is given in the case of hydrogen embrittlement. A fracture toughness transferability curve (K-rho c-T-ef) has been established for the X52 pipe steels described by a linear relationship where T-ef is the average value of T stress over the characteristic length of the fracture process. A mechanism involving influence of the T-ef,T-c-stress on void growth for ductile failure is proposed; the effects of hydrogen on crack paths from the viewpoint of microstructural aspects are disputed. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.